Nerve-extracting needle for dental purposes or the like



F. HAUPTMEYER.- Y NERVE EXTRACTING NEEDLE FOR DENTAL PURPOSES OR THELIKE.

' APPLICATION FILED saw. 3. 1920.

1,402,229, Patented Jan. 3, 1922.

Invent Frmdrich Ha lp g NERVE-EXTRACTIN G NEEDLE FOR DENTAL PURPOSES ORTHE LIKE.

I Specification of Letters Patent.

Patented J an. 3, 1922.

Application filed September 3, 1920. Serial No. 408,084.

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3, 1921, 41 STAT. L,1313.)

T 0 all whom it may concern:

Be it known that Dr. FRIEDRICH HAUPT- MEYER, a citizen of Germany, resding at Essen, Germany, has invented certain new and useful Improvementsin Nerve-Extracting Needles for Dental Purposes-or the like, (for whichI have filed application in Germany May 27, 1919,) of which thefollowing is a specification.

The invention refers to needles or similar instruments for dental orsimilar purposes consisting of chromium-.nickel-steel, alloys instead ofordinary steel. Chromiumnickel-steel alloys particularly Withstand theeii'ects of certain acids or similar substances, and this property isparticularly characteristic of chromium-nickel-steel alloys containingabout 18 to 23 per cent chromium, 10 to 5 per cent nickel, and 0.1 to0.4 per cent carbon.

Particularly in dentistry which uses destructive chemicals such as acquaregia, sulphuric acid, phenyl chloride, formaldehyde and the like, finepoints of nerve extracting needles or similar instruments when made ofordinary steel are particularly subject to deterioration anddestruction. Precious metals cannot be used generally for this purtionswhich are difiicult to remove, nerve pose because they lack thenecessary strength and hardness. Electroplating of such steel needleswith precious metals is not practical on account of the fine pointsrequired on these needles.

Fiu thermore, ordinary steel is not practical for needles of this kindon account of the danger which is incurred through broken ofi pieceswhich may remain in the teeth. Owing to the inflammation and abscessescaused by such broken needle por-

